Impacts of ACE insertion/deletion variant on cardiometabolic risk factors, premature coronary artery disease, and severity of coronary lesions

Angiotensin-converting enzyme (ACE) is closely related to cardiometabolic risk factors and atherosclerosis. This study aims to investigate whether the insertion/deletion (I/D) variant of ACE gene impacts cardiometabolic risk factors, premature coronary artery disease (PCAD), and severity of coronary lesions. PubMed, Cochrane Library, Central, CINAHL, and ClinicalTrials.gov were searched until December 22, 2023. 94,270 individuals were included for the analysis. Carriers of DD genotype had higher levels of triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), and waist circumference (WC) than carriers of II or ID genotypes. In addition, carriers of DD genotype were at high risk of PCAD and multiple vessel lesions. The impacts of ACE I/D variant on lipid levels were significant in American individuals but stronger in male individuals. In contrast, the impacts of ACE I/D variant on PCAD and severity of coronary lesions were primarily significant in Caucasian individuals. This study indicates that the ACE I/D variant has a slight but significant impact on cardiometabolic risk factors, PCAD, and severity of coronary lesions. Angiotensin-converting enzyme inhibitors (ACEI) may benefit high-risk populations with ACE DD genotype to prevent PCAD and multiple vessel lesions. PROSPERO registration number: CRD42023426732


Impact of the ACE I/D variant on the risk of PCAD
The DD genotype increased the risk of PCAD compared with II or ID genotypes (Fig. 4).Subgroup analysis indicated that the impact of the ACE I/D variant on PCAD risk was primarily significant in Caucasian and male individuals (Table 2).

Impact of the ACE I/D variant on the severity of coronary lesions
The DD genotype increased the risk of multiple vessel lesions compared with II or ID genotypes (Fig. 5).Subgroup analysis indicated that the impact of the ACE I/D variant on multiple vessel lesions was significant in Caucasian and other ethnicities individuals (Table 3).

Publication bias test
Begg funnel plot was used to evaluate publication bias among the included studies.This meta-analysis had no publication bias, which was confirmed by the Egger linear regression test.

Discussion
The present study indicated that the DD genotype of the ACE I/D variant increased the risk of PCAD (Table 2) and multiple vessel lesions (Table 3), as well as elevated TG, TC, LDL-C, SBP, DBP, BMI, and WC (Table 1).Since dyslipidemia, hypertension, high BMI, and large WC were considered the primary risk factors for PCAD and multiple vessel lesions 16,17 , it indicated that the increased risk of PCAD (Table 2) and multiple vessel lesions (Table 3) associated with DD genotype was attributed, at least partly, by the impacts of the ACE I/D variant on TG, TC, LDL-C, SBP, DBP, BMI, and WC (Table 1).
Subgroup analyses by sex revealed that the impact of the ACE I/D variant on PCAD was significant in male individuals (Table 2).Since the impacts of the ACE I/D variant on LDL-C, TC, SBP, and DBP were significant in male individuals (Table 1), it indicated that the impact of the ACE I/D variant on PCAD in male individuals (Table 2) was at least partly mediated by the elevated LDL-C, TC, SBP, and DBP (Table 1).In addition, subgroup analyses by race showed that the impacts of the ACE I/D variant on PCAD and multiple vessel lesions were significant in Caucasian individuals (Tables 2, 3).Since the impact of the ACE I/D variant on SBP was significant in Caucasian individuals (Table 1), it indicated that the impacts of the ACE I/D variant on PCAD and CAD severity in Caucasian individuals (Tables 2, 3) were partially mediated by the elevated SBP (Table 1).
In this study, the prevalence of II genotype in Caucasian individuals, American individuals, Asian individuals, and other ethnicities individuals was 0.40 (range from 0.08 to 0.72), 0.43 (range from 0.22 to 0.64), 0.50 (range from 0.22 to 0.78), and 0.535 (range from 0.22 to 0.85), respectively.In contrast, the prevalence of DD genotype in Caucasian individuals, American individuals, Asian individuals, and other ethnicities individuals was 0.325 (range from 0.15 to 0.50), 0.275 (range from 0.18 to 0.37), 0.23 (range from 0 to 0.46), and 0.17 (range from 0.04 to 0.30), respectively.In addition, the prevalence of ID genotype in Caucasian individuals, American individuals, Asian individuals, and other ethnicities individuals was 0.275 (range from 0.22 to 0.33), 0.295 (range from 0.18 to 0.41), 0.27 (range from 0.205 to 0.335), and 0.295 (range from 0.15 to 0.44), respectively.
The impacts of the ACE I/D variant on PCAD and the severity of coronary lesions were primarily significant in Caucasian individuals, but not in Asian individuals and other ethnicities individuals (Tables 2, 3).One particular reason could be proposed to interpret this phenomenon.That is, Caucasian individuals had a higher carrying rate of DD than Asian and other ethnicities individuals (Caucasian individuals vs. Asian individuals vs.Other ethnicities individuals = 0.325 vs. 0.23 vs. 0.17).Similarly, since the prevalence rate of DD was relatively higher in American individuals than in Asian individuals and other ethnicities individuals (American individuals vs. Asian individuals vs. other ethnicities individuals = 0.275 vs. 0.23 vs. 0.17), it is plausible to observe that the impacts of the ACE I/D variant on cardiometabolic parameters (Table 1) were primarily significant in American individuals.
According to the 2018 American College of Cardiology (ACC)/American Heart Association (AHA) 24 , the 2019 European Society of Cardiology (ESC)/European Atherosclerosis Society (EAS) 25 , and the Adult Treatment Panel III (ATP III) cholesterol guidelines 26 , LDL-C was considered the major cause of CAD and treated as the primary target for therapy, while other lipids were used as the secondary or supplementary therapeutic targets.In this study, the strongest impact of the ACE I/D variant on LDL-C levels was detected in male individuals (SMD = 0.30, 95% CI 0.15 to 0.45, P = 0.03) (Table 1).It indicated that male individuals with DD were at a very high risk of CAD.In addition, the impact of the ACE I/D variant on LDL-C levels was also significant in American individuals (Table 1), suggesting that American individuals with DD were at high risk of CAD.
A small sample case-control study conducted by Winkelmann and colleagues 27 included 209 male patients with CAD and 92 male controls and found that the ACE I/D variant was not associated with an increased risk for CAD or myocardial infarction (MI).In contrast, a moderate-scale case-control study conducted by Cambien and colleagues 28 included 610 patients with MI and 733 controls and found that the ACE I/D variant was a potent risk factor for CAD in subjects formerly considered to be at low risk according to common criteria.In addition, Miao et al. 29 , Zhou et al. 30 , and Zhang et al. 31 21,22,[32][33][34][35][36][37][38][39][40] .Taken together, the correlation between the ACE I/D variant and CAD appears to be related to the sample size of studies.In which, studies with small samples are unlikely to detect the true impact of the ACE I/D variant on CAD, whilst studies with relatively larger samples may detect the true association between the ACE I/D variant and CAD due to adequate statistical power.The present meta-analysis included 3195 patients with PCAD and 2395 patients with multiple vessel lesions and found that the DD genotype significantly increased the risk of PCAD and multiple vessel lesions by 9% and 4%, respectively, suggesting that the ACE I/D variant was slightly but significantly associated with PCAD and multiple vessel lesions (Tables 2, 3).In line with these findings, this meta-analysis also indicated that the DD genotype significantly increased TG, TC, LDL-C, SBP, DBP, BMI, and WC (Table 1).It indicated that the impacts of the ACE I/D variant on PCAD and the severity of coronary lesions (Tables 2, 3) were at least partly mediated by the impacts of the ACE I/D variant on cardiometabolic risk factors (Table 1).
The impacts of the ACE I/D variant on cardiometabolic risk factors, PCAD, and severity of coronary lesions (Tables 1, 2 and 3) were essentially attributed to high levels of ACE [7][8][9][10][11][12][13][14]16,17 . SinceACEI/angiotensin receptor blockers (ARBs) were prominent inhibitors of ACE that had been widely used in clinical practice 41 , it is tempting to hypothesize that preventive use of ACEI/ARBs may benefit high-risk populations with the DD genotype to prevent cardiometabolic disorder, PCAD, and multiple vessel lesions.Further randomized controlled trials (RCTs) are needed to verify this hypothesis and detail the dose, frequency, and duration of administration.Since the DD genotype was closely linked to cardiometabolic disorder (Table 1), PCAD (Table 2), and multiple vessel lesions (Table 3), the genetic screening of the ACE I/D variant may benefit the early prevention or control of PCAD and multiple vessel lesions.
The connection between genotype and phenotype is intricate.For instance, the genotypes may generate complex clinical phenotypes, which can be further modified by external factors (e.g.environmental factors and lifestyles).In other words, the clinical phenotypes of individual organisms are jointly determined by multiple factors (e.g.genetic factors, environmental factors, and personal lifestyles).Additionally, there are often many genotypes that produce the same phenotype, adding a layer of complexity in establishing valid genotype-phenotype relationships 42 .Therefore, prediction of trait heritability via genotype-phenotype association remains a major challenge in modern genetics.How to reasonably regulate the trait inheritance association with heterogeneous genotype-phenotype is becoming an important field of biological research and application, and it is also the prerequisite and foundation to execute gene editing and gene therapy.
The present meta-analysis has several strengths (1) all results are recalculated after excluding the studies with heterogeneity (Table 1), which advances the preciseness of conclusions drawn in this paper; (2) the conclusions will no doubt benefit clinicians to make the optimum management strategies for high-risk population with the DD genotype to prevent PCAD or multiple vessel lesions; (3) genetic screening of the DD genotype is critical for the high-risk population to prevent PCAD or multiple vessel lesions.In addition, several limitations should be noted (1) there is no information regarding the moment of measurement (on treatment or without treatment); (2) CAD is a multifactorial disease, and the major risk factors include genetic factors, environmental influences, and personal lifestyles.To explain the role of specific mutation (e.g.ACE I/D variant), all relevant risk factors (i.e.genetic factors, environmental influences, and personal lifestyles) should be explored.However, the impacts of environmental factors and personal lifestyles associated with the ACE I/D variant on PCAD and CAD severity, as well as the interactions of the ACE I/D variant with environmental factors and personal lifestyles on PCAD and CAD severity have yet to be investigated in the present meta-analysis due to the lack of original data from the included studies.In other words, more precise results could have been gained if more detailed individual data were available or the stratification analyses based on environmental factors and personal lifestyles, such as diet, exercise, smoking, alcohol consumption, etc., were performed; (3) there was no study investigated the impact of ACE I/D variant on PCAD in Asian individuals, American individuals, and female individuals (Table 2).More comprehensive and diversified results would be available if more studies on specific populations (e.g.Asian individuals, American individuals, and female individuals) were carried out.

Materials and methods
The current meta-analysis follows the Preferred Reporting Items for Systematic Reviews and Meta-analyses (see Table S2 for more details) 43 .

Inclusion criteria
The

Data extraction
The data extraction was conducted by ZL.From each included study, the following was extracted: the last name of the first author; publication time; country, race, sex, age, case and control counts, genotype count, study design,

Figure 1 .
Figure 1.Flow diagram of the studies selection process.
respectively conducted a meta-analysis (sample size: 1241 cases and 3452 controls for Miao et al. 5215 cases and 4782 controls for Zhou et al. 5619 cases and 4865 controls for Zhang et al.) to investigate the association between ACE I/D variant and the risk of CAD.Intriguingly, all three mete-analyses demonstrated that there was a significant association between ACE I/D variant and CAD [odds ratio (OR) = 1.92 for Miao et al., OR range from 1.19 to 2.40 for Zhou et al., OR = 1.95 for Zhang et al.].In line with previous clinical trials

Figure 2 .
Figure 2. Forest plot of the meta-analysis between ACE DD genotype and low-density lipoprotein cholesterol levels.

Figure 3 .
Figure 3. Forest plot of the meta-analysis between ACE DD genotype and systolic blood pressure levels.

Figure 4 .
Figure 4. Forest plot of the meta-analysis between ACE DD genotype and premature coronary artery disease risk.
inclusion criteria for the impacts of the ACE I/D variant on PCAD and CAD severity include (1) case-control design; (2) CAD cases were angiographically defined; (3) studies provided the number of individual genotypes in cases and controls for the ACE I/D variant; (4) studies provided the number of individual genotypes in multiple (≥ 3) and non-multiple (< 3) lesions for the ACE I/D variant.The inclusion criteria for the impacts of the ACE I/D variant on cardiometabolic risk factors include (1) studies investigated the association of ACE I/D variant with lipid [including four lipid parameters, i.e.TG, TC, LDL-C, and HDL-C, rather than other lipoproteins, e.g.apolipoprotein B (APOB), apolipoprotein E (APOE), and apolipoprotein A1 (APOA1), etc.; expressed as mean with standard deviation (SD) or standard errors (SE), but not other forms, such as, mean with 95% confidence intervals (CI) and median with interquartile range (IQR); data of dyslipidemia and normal lipid levels were available]; (2) studies investigated the association of ACE I/D variant with blood pressure (including SBP and DBP; expressed as mean with SD or SE; data of hypertension and normal blood pressure levels were available); (3) studies investigated the association of the ACE I/D variant with FPG (rather than postprandial plasma glucose; expressed as mean with SD or SE; data of dysglycemia and normal plasma glucose were available); (4) studies investigated the association of ACE I/D variant with BMI [expressed as mean with SD or SE; data of underweight (< 18.5 kg/m 2 ), overweight (25-29.9kg/m 2 ), obesity (> 30 kg/m 2 ), and normal range (18.5-24.9kg/m 2 ) were available]; (5) studies investigated the association of ACE I/D variant with WC (expressed as mean with SD or SE); (6) studies provided the number of individual genotypes for the ACE I/D variant; (7) the language of eligible studies was restricted to English.The exclusion criteria of this meta-analysis include (1) studies that were not related to the ACE I/D variant; (2) studies that were not related to cardiometabolic risk factors; (3) studies that were not related to PCAD or CAD severity; (4) studies not presenting genotype count in controls, or the genotype distribution of controls deviate from the Hardy-Weinberg equilibrium (HWE); (5) studies having invalid data; (6) studies having incomplete data; (7) pedigree studies; (8) overlapping studies; and (9) abstract, review, case report, meta-analysis, and animal studies.

Figure 5 .
Figure 5. Forest plot of the meta-analysis between ACE DD genotype and severity of coronary lesions.

Table 2 .
Meta-analysis of the ACE I/D variant with premature coronary artery disease.ACE angiotensin converting enzyme gene, RR risk ratios, 95% CI 95% confidence interval, P H P for heterogeneity.